1. Field of the Invention
The present invention relates to a contact arrangement for a vacuum interrupter (or called, a vacuum switch) and the vacuum interrupter using the contact arrangement.
2. Description of the Related Art
In order to improve a breaking capacity (or interruption performance) of such a kind of vacuum interrupter as described above, it is necessary to receive arc with a whole surface of each contact without a concentration of the arc developed in a gap between both of contacts during a power interruption on a single portion of each contact electrode.
A longitudinal magnetic field application system (viz., a technique of providing coil electrodes to apply a magnetic field in an axial direction parallel to an axis of the arc generated between a pair of contact electrodes during an interruption) has been adopted in such a vacuum interrupter as described above.
The generated arc is enclosed by the magnetic field when the longitudinal magnetic field is applied across the contact electrodes. A loss from an arc column of charge particles becomes reduced, the arc becomes stable, a temperature rise in the contact electrodes is suppressed, and the breaking capacity is improved.
A Japanese Patent Application Second (Examined) Publication No. Heisei 3-59531 published on Sep. 10, 1991 (which corresponds to a U.S. Pat. No. 4,620,074 issued on Oct. 28, 1986) exemplifies a previously proposed vacuum switch in which the longitudinal magnetic field application system has been adopted. In the above-described Japanese Patent Application Second Publication, a hollow cylindrical contact carrier for supporting a contact plate having a cup depth is provided for each of a pair of cup-type contact electrode, the contact electrodes are arranged coaxially opposite to each other, and each contact carrier has a plurality of slots (or called, a plurality of slits) inclined in the same sense with respect to a longitudinal axis of each contact electrode. Then, a cup depth, the number of slots, and an azimuth angle of each of the slots are prescribed.
However, if the previously proposed vacuum switch disclosed in the above-described Japanese Patent Application Second Publication, the arcs developed between the contact electrodes become unstable due to an insufficient magnetic flux density between the contact electrodes and, in worst case, the contact electrodes cannot interrupt the power. In addition, if the azimuth angle of each of the slits formed on the contact carrier is considerably widened, a mechanical strength of each contact electrode itself becomes insufficient. Then, if each contact electrode is deformed due to an operational force of opening (disconnecting) or closing (connecting) each contact electrode so that a voltage withstanding characteristic and a power interruption characteristic might be worsened.
It is, hence, an object of the present invention to provide a contact arrangement for a vacuum interrupter and vacuum interrupter using the contact arrangement in which the longitudinal magnetic field application system is adopted and which are favorable in the voltage withstanding characteristic and power interruption characteristic even if the diameter of each contact electrode and the separation distance therebetween are widened.
According to one aspect of the present invention, there is provided a contact arrangement for a vacuum interrupter, comprising: a hollow cylindrical contact carrier on one end surface of which a contact plate is attached; a plurality of first slits formed on the contact carrier from the one end surface of the contact carrier; and a plurality of second slits formed on the contact carrier from each predetermined point of midway through an axial direction of the contact carrier, each of the first and second slits being tilted with respect to the axial direction of the contact carrier, a coil portion being formed on a portion of the hollow cylindrical contact carrier between each of the first and second slits and an adjacent one of the first and second slits, and a longitudinal magnetic field being formed along the axial direction of the contact carrier by a current flowing on the coil portion.
According to another aspect of the present invention, there is provided a vacuum interrupter having a pair of contact electrodes arranged on the same axis in an evacuated envelope in a manner to connect or disconnect with each other by respective electrode rods, at least one contact electrode comprising: a hollow cylindrical contact carrier on one end surface of which a contact plate is attached; a plurality of first slits formed on the contact carrier from the one end surface of the contact carrier; and a plurality of second slits formed on the contact carrier from each predetermined point of midway through an axial direction of the contact carrier, each of the first and second slits being tilted with respect to the axial direction of the contact carrier, a coil portion being formed on a portion of the hollow cylindrical contact carrier between each of the first and second slits and an adjacent one of the first and second slits, and a longitudinal magnetic field being formed along the axial direction of the contact carrier by a current flowing on the coil portion.
This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.